Posts Tagged ‘biodiversity’

Experts share their insights on the link between biodiversity loss and emerging infectious diseases.

This story by Alison Doody was originally posted on the website of the International Maize and Wheat Improvement Center (CIMMYT). The views and opinions expressed are those of the authors and do not necessarily reflect the official policy or position of CIMMYT.

Forests in the land of the Ese’eja Native Community of Infierno, in Peru’s Madre de Dios department. (Photo: Yoly Gutierrez/CIFOR)

While the world’s attention is focused on controlling COVID-19, evidence points at the biodiversity crisis as a leading factor in its emergence. At first glance, the two issues might seem unrelated, but disease outbreaks and degraded ecosystems are deeply connected. Frédéric Baudron, systems agronomist at the International Maize and Wheat Improvement Center (CIMMYT) and Florian Liégeois, virologist at the Institut de Recherche pour le Développement (IRD) share their insights on the current COVID-19 crisis and the link between biodiversity loss and emerging infectious diseases.

What trends are we seeing with infectious diseases like COVID-19?

We see that outbreaks of infectious diseases are becoming more frequent, even when we account for the so-called “reporting bias::” surveillance of such events becoming better with time and surveillance being better funded in the North than in the South.

60% of infectious diseases are zoonotic, meaning that they are spread from animals to humans and 72% of these zoonoses originate from wildlife. COVID-19 is just the last in a long list of zoonoses originating from wildlife. Other recent outbreaks include SARS, Ebola, avian influenza and swine influenza. As human activities continue to disturb ecosystems worldwide, we are likely to see more pathogens crossing from wildlife to humans in the future. This should serve as a call to better manage our relationship with nature in general, and wildlife in particular.

Why are we seeing more cases of diseases crossing from animals to humans? Where are they coming from?

Evidence points to bushmeat trade and consumption as the likely driver for the emergence of COVID-19. The emergence of SARS and Ebola was also driven by bushmeat consumption and trade. However, when looking at past outbreaks of zoonoses caused by a pathogen with a wildlife origin, land use changes, generally due to changes in agricultural practices, has been the leading driver.

Pathogens tends to emerge in well known “disease hotspots,” which tend to be areas where high wildlife biodiversity overlaps with high population density. These hotspots also tend to be at lower latitude. Interestingly, many of these are located in regions where CIMMYT’s activities are concentrated: Central America, East Africa and South Asia. This, in addition to the fact that agricultural changes are a major driver of the emergence of zoonoses, means that CIMMYT researchers may have a role to play in preventing the next global pandemic.

Smallholders clear forests for agriculture, but they also have an impact on forests through livestock grazing and fuelwood harvesting, as on this picture in Munesa forest, Ethiopia. (Photo: Frederic Baudron/CIMMYT)

How exactly does biodiversity loss and land use change cause an increase in zoonotic diseases?

There are at least three mechanisms at play. First, increased contact between wildlife and humans and their livestock because of encroachment in ecosystems. Second, selection of wildlife species most able to infect humans and/or their livestock — often rodents and bats — because they thrive in human-dominated landscapes. Third, more pathogens being carried by these surviving wildlife species in simplified ecosystems. Pathogens tend to be “diluted” in complex, undisturbed, ecosystems.

The fast increase in the population of humans and their livestock means that they are interacting more and more frequently with wildlife species and the pathogens they carry. Today, 7.8 billion humans exploit almost each and every ecosystem of the planet. Livestock have followed humans in most of these ecosystems and are now far more numerous than wild vertebrates: there are 4.7 billion cattle, pigs, sheep and goats and 23.7 billion chickens on Earth! We live on an increasingly “cultivated planet,” with new species assemblages and new opportunities for pathogens to move from one species to another.

Wildlife trade and bushmeat consumption have received a lot of attention as primary causes of the spread of these viruses. Why has there been so little discussion on the connection with biodiversity loss?

The problem of biodiversity loss as a driver of the emergence of zoonoses is a complex one: it doesn’t have a simple solution, such as banning wet markets in China. It’s difficult to communicate this issue effectively to the public. It’s easy to find support for ending bushmeat trade and consumption because it’s easy for the public to understand how these can lead to the emergence of zoonoses, and sources of bushmeat include emblematic species with public appeal, like apes and pangolins. Bushmeat trafficking and consumption also gives the public an easy way to shift the blame: this is a local, rather than global, issue and for most of us, a distant one.

There is an inconvenient truth in the biodiversity crisis: we all drive it through our consumption patterns. Think of your annual consumption of coffee, tea, chocolate, sugar, textiles, fish, etc. But the biodiversity crisis is often not perceived as a global issue, nor as a pressing one. Media coverage for the biodiversity crisis is eight times lower than for the climate crisis.

Agriculture is a major cause of land use change and biodiversity loss. What can farmers do to preserve biodiversity, without losing out on crop yields?

Farming practices that reduce the impact of agriculture on biodiversity are well known and form the foundation of sustainable intensification, for which CIMMYT has an entire program. A better question might be what we can do collectively to support them in doing so. Supportive policies, like replacing subsidies by incentives that promote sustainable intensification, and supportive markets, for example using certification and labeling, are part of the solution.

But these measures are likely to be insufficient alone, as a large share of the global food doesn’t enter the market, but is rather consumed by the small-scale family farmers who produce it.

Reducing the negative impact of food production on biodiversity is likely to require a global, concerted effort similar to the Paris Agreements for climate. As the COVID-19 pandemic is shocking the world, strong measures are likely to be taken globally to avoid the next pandemic. There is a risk that some of these measures will go too far and end up threatening rural livelihoods, especially the most vulnerable ones. For example, recommending “land sparing” — segregating human activities from nature by maximizing yield on areas as small as possible — is tempting to reduce the possibility of pathogen spillover from wildlife species to humans and livestock. But food production depends on ecosystem services supported by biodiversity, like soil fertility maintenance, pest control and pollination. These services are particularly important for small-scale family farmers who tend to use few external inputs.

How can we prevent pandemics like COVID-19 from happening again in the future?

There is little doubt that new pathogens will emerge. First and foremost, we need to be able to control emerging infectious diseases as early as possible. This requires increased investment in disease surveillance and in the health systems of the countries where the next infectious disease is most likely to emerge. In parallel, we also need to reduce the frequency of these outbreaks by conserving and restoring biodiversity globally, most crucially in disease hotspots.

Farming tends to be a major driver of biodiversity loss in these areas but is also a main source of livelihoods. The burden of reducing the impact of agriculture on biodiversity in disease hotspots cannot be left to local farmers, who tend to be poor small-scale farmers: it will have to be shared with the rest of us.

Any fifth grader is familiar with the Cretaceous-Tertiary mass extinction, which saw dinosaurs — and three quarters of all species alive at that time — disappear from Earth, probably after it was struck by a very large asteroid. However, few people are aware the planet is currently going through a similar event of an equally large magnitude: a recent report from the World Wide Fund for Nature highlighted a 60% decline in the populations of over 4,000 vertebrate species monitored globally since 1970. This time, the culprit is not an asteroid, but human beings. The biggest threat we represent to other species is also the way we meet one of our most fundamental needs: food production.

As a response, scientists, particularly ecologists, have looked for strategies to minimize trade-offs between agriculture and biodiversity. One such strategy is “land sparing,” also known as the “Borlaug effect.” It seeks to segregate production and conservation and to maximize yield on areas as small as possible, sparing land for nature. Another strategy is “land sharing” or “wildlife-friendly farming,” which seeks to integrate production and conservation in the same land units and make farming as benign as possible to biodiversity. It minimizes the use of external inputs and retains unfarmed patches on farmland.

A heated debate between proponents of land sparing and proponents of land sharing has taken place over the past 15 years. Most studies, however, have found land sparing to lead to better outcomes than land sharing, in a range of contexts. With collaborators from CIFOR, UBC and other organizations, I hypothesized that this belief was biased because researchers assessed farming through a narrow lens, only looking at calories or crop yield.

Many more people today suffer from hidden hunger, or lack of vitamins and minerals in their diets, than lack of calories. Several studies have found more diverse and nutritious diets consumed by people living in or near areas with greater tree cover as trees are a key component of biodiversity. However, most of these studies have not looked at mechanisms explaining this positive association.

Forests for food

Studying seven tropical landscapes in Bangladesh, Burkina Faso, Cameroon, Ethiopia, Indonesia, Nicaragua and Zambia, we found evidence that tree cover directly supports diets in four landscapes out of seven. This may be through the harvest of bushmeat, wild fruits, wild vegetables and other forest-sourced foods. The study further found evidence of an agroecological pathway — that forests and trees support diverse crop and livestock production through an array of ecosystem services, ultimately leading to improved diets — in five landscapes out of seven. These results clearly demonstrate that although land sparing may have the best outcomes for biodiversity, it would cut off rural households from forest products such as forest food, firewood and livestock feed. It would also cut off smallholder farms from ecosystem services provided by biodiversity, and smallholders in the tropics tend to depend more on ecosystem services than on external inputs.

In Ethiopia, previous research conducted by some of the same authors has demonstrated that multifunctional landscapes that do not qualify as land sparing nor as land sharing may host high biodiversity whilst being more productive than simpler landscapes. They are more sustainable and resilient, provide more diverse diets and produce cereals with higher nutritional content.

The debate on land sparing vs. sharing has largely remained confined to the circles of conservation ecologists and has seldom involved agricultural scientists. As a result, most studies on land sparing vs. sharing have focused on minimizing the negative impact of farming on biodiversity, instead of looking for the best compromises between agricultural production and biodiversity conservation.

To design landscapes that truly balance the needs of people and nature, it is urgent for agronomists, agricultural economists, rural sociologists and crop breeders to participate in the land sparing vs. sharing debate.

This study was made possible by funding from the UK’s Department for International Development (DFID), the United States Agency for International Development (USAID) through the project Agrarian Change in Tropical Landscapes, and by the CGIAR Research Programs on MAIZE and WHEAT.

Efforts to preserve wheat biodiversity help crops, farmers and consumers

For more than 8000 years in an area that now includes Turkey and Afghanistan
hundreds of local varieties — or landraces— evolved to be uniquely adapted to
their environment and ideally suited for local production and consumption. Over the
years, for economic reasons, many farmers have adopted higher-yielding modern
varieties, with only small subsistence farmers in remote areas still growing
ancient landraces. In Turkey, for
example, a 2009 study showed
the share of local landraces was under 1 percent of the total wheat production
area.

Finding, identifying and conserving these local varieties not only safeguards the great biodiversity of wheat in the world, but also helps state of the art efforts to develop resistance to pests and disease, tolerance to environmental stresses and more nutritious wheat.

To complete the cycle, they plan to distribute the seeds of
these improved landraces to farming communities in the target provinces and offer
training on sustainably cultivating their unique landraces to maintain biodiversity
in their fields.

“These landraces are very important to small farmers in
remote mountainous regions,” said Morgunov.
“And they are rich source of genetic traits to fight future threats to wheat
production.”

“We are honored to help farmers keep these varieties alive
in their fields.”

Diversity is beneficial for not only wheat health, but human
health as well. A conference this fall in Istanbul
will bring wheat researchers and the health community together to share
progress and discuss strategies for improving the health benefits of wheat
using diverse genetic resources.